There is a known method for liquid-phase catalytic alkylation of aniline, disclosed in RU 2270831 C1, publ. 27 Feb. 2006. The method involves the alkylation of aniline in the presence of hydrogen and a fixed palladium catalyst in ethyl or methyl alcohol at a temperature of 55-65° C. and a pressure of 0.2-0.4 MPa. In this case, alkylation is carried out with formalin at aniline:formalin ratio of 1.6/1.1, the process is carried out in a cylindrical reactor mounted on a rocking chair with a swing number of 120-160 min−1, in the middle part of which is placed a porous block cellular palladium catalyst, active layer of which is modified by palladium nanoparticles, with a porosity of 70-95% and a palladium content of 1.8-3.7%, with hydrogen being fed through the fitting of the reactor lid.
The disadvantage of the prior art method is the low yield of N-methylanilian (not more than 55%).
The closest analogue of the claimed invention is a method of liquid-phase catalytic alkylation of aromatic amines, disclosed in RU 2285691 C1, publ. 20 Oct. 2006. The method includes the alkylation of aromatic amines on a heterogeneous catalyst in the presence of hydrogen and lower alcohols at a temperature of 50-70° C. Alkylation is carried out with formalin in a reactor with a reaction zone filled with a catalyst consisting of a block highly porous cellular alumina carrier with a porosity in the 70-95% and the active component, which is palladium with a mass content equal to 1.3-2.0%.
The disadvantage of the closest analogue is the low yield of N-methylanilian (not above 57%).
Alkylation of para-anisidine under the conditions described in patent RU 2285691 resulted in a similar, low yield of N-methyl-para-anisidine and high values of the dimethyl derivant, which does not allow to consider this method acceptable for industrial production of the desired product N-methyl-para-anisidine.